Motor control system



' Jan. 19, 1932. R. P. HIGBEE 1,841,601

MOTOR CONTROL SYSTEM I Filed Feb. 17, 1928 2 Sheets-Sheet 1 WITN ESS E51 INVENTOR fiay P. ffl'gee fiezummf ATTORNEY Jan. 19, 1932. R. P. HIGBEE MOTOR CONTROL SYSTEM Filed Feb. 17, 1928 2 Sheets-Sheet 2 I 7 7 a Z 0 afiwm Er 8 9 m F .r, L m JL M INVENTOR Ray E H/ybee' ATTORNFY III/I m m z WITNESSES- Patented Jan. 19, 1932 UNITED STATES PATENT OFFICE RAY P. E1633], GEBKANTOWN, PENNSYLVANIA, AS SIGNOB '10 WESTINGHOUSE ELECTRIC & KAHUFACTUBIIG OOIPAIY, A CORPORATION 01' PENNSYLVANIA IO'I'OB CONTROL Sm Application fled Zl'ebrnary 17, 1928. Serial Io. 254,968.

My invention relates to motor-control systems, and has special relation to control systems for elevators, hoists and similar 'machinery.

An object of m invention is to provide a control system or machines, operable in either of two directions, to achieve a dynamic-braking condition when the machine is to be stopped after travelling in either of the m directions.

Another object of my invention is to provide a control system for an alternating-current motor, wherein a dynamic-braking efiect will be achieved when the motor is to be stopped.

automatically set up for producing a dynamic-braking effect which will continue until the motor has reached a zero speed.

Another object of my invention is to rovide a control system for an elevator driven 1'? by an alternating-current motor, wherein the elevator will be brought to a stop entirely through the effect of a dynamic-braking condition automatically set up by the elevator when the motor is to be stopped.

Other objects of my invention will be set forth in the accompanying descri tion.

One form of my invention is il ustrated in the accompanying drawings, wherein;

Figure 1 is a diagrammatic view of an ele- 5 vator system provided with my dynamicbraking devices.

Fig. 2 is a plan view of one of two relative- 1y movable elements of a switching device embodying my invention,

' Fig. 3 is a view in front elevation of the switch device shown in Fig. 2, and,

, Fig. 4 is a view in section taken on the line IV--IV of Fig. 3, and including the other of the two relatively movable elements of my switching device.

It is a characteristic of an alternatingcurrent motor that, when it is to be decelerated from a hlgh speed, a dynamic-braking effect may be achieved by reversing the current supplied to it. It is my intentlon to utilize this characteristic, in order to produce 'an efiicient dynamic-braking condition whenever it is desired to reduce the speed of an elevator in making a stop.

Referring to Fig. 1 of the drawings, I have illustrated an elevator car C suspended upon the usual cable Ca and extendin over a drum D to a suitable counter-weight Suitabl coupled to the hoisting drum D, as by a she 3, is the rotor R of a squirrel-cage motor M, the stator S of which is wound for connection to a threehase source of alternating-current energy. he direction of operation of the motor M is suitably controlled through the operation of the up-direction and down-direction switches designated by the reference characters 1 and 2, respectively, which switches are, in turn, controlled through the operation of a suitable car switch Cs mounted upon the elevator car C.

Referring now to Figures 2, 3 and 4, the shaft, which couples the motor M to the hoisting drum D, 1s provided with an exten- $101 4, carrying a cup shaped member 5 which is thus made rotatable with the mo tor M. Suitably mounted upon'a supporting arm 6, is a lever 7, one end 8 of which acts as a bearing for a stub shaft 9 upon which a friction segment 10 is rotatably mounted, to lie within the cup 5 and engage therewith to constitute a friction clutch. To provide a suitable bearing surface for the segment 10, I have provided a sleeve 11 upon which a contact segment 12 is also suitably insulatingly mounted through the interposition of F5 abl and non-rotatably mounted on the outer en 8 of lever 7. By reason of this construction, any rotation of thefriction segment 10 causes a similar movement of the contact so cut 12 over the cooperating contact brushes 15,16, etc.

As will be observed from an inspection of Fi 4, the friction segment 10 is so mounted ad]acent to the cup-like member 5 as to lie wholly within it, with the friction face 23 adjacent to the inner face of the flange 24. The frictional engagement between the cup member 5 and the friction segment will cause rotation of the former to be transmitted to the contact se ment 12.

In order to increase the coefiicient of fric tion between the cup member 5 and the friction segment 10, I have illustrated a lining 25 of suitable material secured to the face 23.

The lever 7, carryin the friction member and the contact brus es, is pivoted upon member 6 closely adjacent to the end 8 by means of a suitable pivotal bearing 26, and the lever 7 has its opposite end 27 suitably coupled to a core 28 of a solenoid 29. By suitably selecting the length of the lever on the opposite sides of the pivot 26, the friction segment 10 may be caused to engage the cup member 5 only when the solenoid 29 is energized. For purposes of clarity, the parts have been illustrated in the position assumed thereby when the solenoid 29 is energized. It will be understood that when the solenoid 29 is deenergized, the lever 7 rotates in a clockwise direction under the influence of a spring 7a to disengage the frictional surfaces.

Assuming that the motor shaft 4 is operating in the direction of the arrow (Fig. 3), the energization of the solenoid 29 will cause enga ement of the faces 24 and 25, and the member 10 will be rotated in the same direction. The contact segment 12 will be carried from the position illustrated in 3 to a position in which the member 10 wi l engage a stop member 30 suitably mounted upon the stationary disc 14. Upon deenergization of the solenoid 29, the friction member 10 and the segment 12 will be returned to the illustrated position by gravity, in which position it will remain until the solenoid 29 is again energized.

The operation of my system will be best described with reference to an assumed elevator operation. Assuming that it is desired to move the elevator car upwardly, the attendant on the car C may move the car switch C8 to the left, causin energization of the updirection switch 1 y way of a circuit which extends from line conductor I, through conductors and 41, contact member 43, contact segment 42, and contact member 44 of the car switch C8, conductors 45 and 46, the coil of up-direction switch 1, conductor 47, normally closed contact members a of downdirection switch 2 and conductors 48 and 49, to line conductor II.

The actuation of up-direction switch 1 com letes a circuit for engiigizing the stator win ings S of the motor the circuits for which extend from line conductor 1, through conductor 50, contact members 0 of up-direction switch 1, conductors 51 and 52 and phase winding 53 of the stator S, to the star point 54; from line conductor II, through conductors 49 and 55, contact members b of updirection switch 1, conductor 56, the second phase winding 57, to the star point 54 and from line conductor III, through conductor 58, to the third phase winding 59 of the stator S and to the star point 54. The elevator car will be started upwardly and will continue travelling in this direction until the car switch C8 is returned to the neutral or off position.

When it is desired to stop the elevator car, I propose to reverse the connections of the stator winding S to cause the motor M to act as a dynamic brake to effect deceleration of the elevator. To accomplish this, I have illustrated a contact member 60 engageable by the segment 42 when the car switch Cs is in the illustrated neutral position for completing circuits to the contact members of switching device SW.

Upon centerin the car switch G8, a circuit will be complete for energizing the coil of a relay 61, which circuit extends from line conductor I, through conductors 40 and 41, contact member 43, contact segment 42, and contact member 60 of car switch Cs, conductors 62, 63, contact members 19, 12 and 15 on the switching device SW, conductor64, the coil of relay 61, conductors and 66, contact members d of up-direction switch 1 and conductor 49, to line conductor II. Energization of relay 61 completes a circuit for energizing the coil of solenoid 29, which circuit extends from line conductor I, through conductors 40 and 41, contact member 43, contact segment 42, and contact member 60 of car switch Cs, conductors 62 and 67, contact members a of relay 61, conductors 68 and 69, the coil of solenoid 29 and conductor 70, to line conductor III.

Energization of solenoid 29 will, as previously described, move the friction segment 10 into engagement with rotatable member 5 mounted upon the motor shaft 4, thus transmitting the rotation of the motor to the contact segment 12. The contact segment 12 will be operated in the direction of the arrow to simultaneously engage and connect contact brushes 19, 20 and 21, and to disengage contact member 15. The engagement with contact member 20 will complete an auxiliary circuit for the solenoid 29 to maintain this solenoid energized during the entire time the motor M is moving, this circuit extending, through conductors 40 and 41, contact member ductor 56.

43,- contact segment 42and contact member 60 of car switch Cs, conductors 62 and 63 members. 19, 12 and 20, to conductor 69 and thence, as previously described, for solenoid 29.

The engagement with contact member 21 by contact segment 12 will complete a circuit for the down-direction switch 2, which circuit extends from line conductor I, through conductors and 41, contact member43, contact segment 42, and contact member 60 of car switch Cs, conductors 62 and 63, contact members 19, 12 and 21 of the switch SW and conductors 72 and 73, the coil of down-direction switch 2, contact members a of up-direction switch 1, and conductor 49, to line conductor II.

The operation of down-direction switch 2, will cause current to be supplied to phase winding 53, reviously supplied from phase conductor I) rom phase conductor II by way of conductors 4:9 and 48, contact members I) of down-direction switch 2, and conductor 52. The operation of switch 2 will also cause phase winding 57 (previously supplied with current from phase conductor II) to be supplied with current' from phase conductor I, through conductors and 75. contact members 0 of down-direction switch 2, and con- The effect of this connection of the phase windings of the stator will be to tend to rotate the armature in the direction opposite to the direction in which it is now rotating, and the resultant effect will be that of a dynamic brakin It will be observed that the length of the contact segment 12 is such that, when it is moved into full engaging position with contact member 21, it is disengaged from its contact member 15, thereby opening the circuit for relay 61, thus, when the movement of the contact segment 12 is reversed, the only circuit for solenoid 29 is through contact member 20. Reenergization of relay 61 is prevented at this time since both direction switches 1 and 2 are deenergized, andthe circuit for relay 61 is broken at contact members (1 of these switches.

It will also be observed that the length of contact segment 42 on the car switch C8 is such that contact will be made with contact member just prior to the time at which contact segment 42 is disengaged from contact member 44, controlling up-direction switch 1, thus relay 61 will be energized through the contactmember d of the up-direction switch 1 prior to the deenergization of up-direction switch 1. However, after the initial energization of relay 61, this relay completes a self-holding circuit for itself from phase conductor III through conductor 77 and contact members b of relay 61, and remains energized until the holding circuit is broken at contact member 15.

Hence, the dynamic-braking effect will be tinned until it is disengaged from contact member 20, thereby deenergizing solenoid 29. This reverse movement, however, represents a reverse our travel of only a fraction of an inch and is negligible, as efi'ecting the operation of the elevator.

Thus, it will be observed'that only a very slight reverse rotation of the motor M is required to deenergize the solenoid 29 to permit the contact segment 12 to assume its normal position. It has been observed that this slight reverse motion is not unpleasant or detrimental in the operation of the elevator and it follows that the motor will be brought to a complete stop entirely through the effect of a dynamic-braking condition. It is assumed that the usual mechanical brake is provided for holding the elevator in its stop ed position.

hile I have illustrated the preferred embodiment of my invention, it is understood that this description is illustrative only and I do not desire to be limited to any of the detailsshown, except as defined in the appended claims.

I .claim as my invention: 1

1. In a device for stopping an alternatingcurrent motor operable from a source of power, control means operable to connect said motor to said source for movement in either of two directions and means operable upon actuation of said control means to stop said motor from movement in either direction, for automatically reversing the connections to Said motor and for maintaining said reversed connections until said motor starts in the new direction, said means including switching means, means for engaging said switching means with said motor for movement therewith and operable upon reverse movement of said motor for disengaging said switching means and said motor.

2. In a device for stopping an alternating current motor operable from a source of power, control means operable to connect said motor to said source for movement in either of two directions and means operable upon actuation of said control means to stop said motor from movement in either direction, for automatically reversing the connections to said motor and for maintaining said reversed connections until said motor starts in the new direction, said means including switching means disposed for actuation by movement of said motor in either direction for operating the controlling means for the opposite direction, means for engaging said switching meanswith said motor for movement therewith, and means for selectively actuating said engaging means.

3-5. In an elevator-control system, an elevator. an altcrnating-current motor therefor, a source of energy for said motor, control means for selectively connecting said motor I to said source for movement in either of two directions, a car switch for selectively actuating said controlling means, and means operable, when said car switch is actuated to stop said motor, for automatically reversing the connection of said motor to said source and for maintaining said reversed connection until said motor starts in the reverse direction, including switching means disposed for actuation by movement of said motor in either direction for operating the control means for the opposite direction, means for engaging said switching means with said motor for movement therewith and means controlled by movement of said car switch to stop said motor for actuating said engaging means.

4. In an elevator-control system, an elevator, an alternating-current motor therefor, a source of energy for said motor, control means for connecting said motor to said source for movement in either of two directions, a car switch for selectively actuating said control means, and means operable upon movement of said car switch to stop said motor, for reversing the connections of said motor and for maintaining said reversed connections until said motor starts in the new direction, including a first friction member rotatable in synchronism with said motor, a second friction member normally disengaged from said first member, switch means for completing said reversing connections mounted for actuation by movement of said second member, a magnet operable upon movement of said car switch to stop said elevator for moving said second member into frictional engagement with said first member for mo vement therewith, and means operable upon reversal of movement of said second member for deenergizing said magnet.

5. In a control system for an alternating current motor; a motor; a source of power for said motor; control'means operable to connect said motor to said source for operation in a selected direction; and means for retarding the speed of said motor, including a switching device effective to complete reversed connections between said motor and said source: said switching device comprising two normally disengaged relatively movable elements, one of said elements being movable in accordance with the movements of said motor. and means, responsive to the actuation of said control means to disconnect said motor from said source, for moving said two elements into engagement to complete and maintain said reversed connections while the original direction of rotation of'said motor perslsts.

6. In a control system for an alternating current motor; a motor; a source of ower for said motor; control means opera le to connect said motor to said source for operation in a selected direction; and means for retarding the speed of said motor, including a switching device effective to complete reversed connections between said motor and said source; said switching device compris ing two normally disengaged relatively movable elements, one of said elements being movable in accordance with the movements of said motor, means, responsive to the actuation of said control means to disconnect said motor from said source, for moving said two elements into engagement to complete said reversed connections, and means controlled by the relative position of said two elements when in engagement for maintaining said engaging means effective while the original direction of rotation of said motor persists.

7. In a control system for an alternating current motor; a motor; a source of power for said motor; control means operable to connect said motor to said source for opera tion in a selected direction; and means for retarding the speed of said motor, including a switching device effective to complete reversed connections between said motor and said source; said switching device comprising two normally disengaged relatively movable elements, one of said elements being movable in accordance with the movements of said motor, and means, responsive to the actuation of said control means to disconnect said motor from said source, for moving said other element into engagement with said first named element'for actuation thereby to complete and maintain said reversed connections while the original direction of rotation of said motor persists.

8. In a control system for an alternating current motor, a motor, a source of ower for said motor, control means opera le to connect said motor to said source for operation in a selected direction, means for retarding the speed of said motor, including a switching device operable to complete reverse connections between said motor and said source, two normally disengaged relatively movable elements, one of said elements being movable in accordance with the movement of said motor, the other of said elements being disposed to engage said movable element and be moved thereby to operate said switching device, and means, responsive to the operation of said control means to disconnect said motor from said source, for efiecting the engagement of said two elements.

0. In combination, a motor, a source of power for said motor, control means operable to reversibly start and stop said motor, switching means actuable in response to the operation of said control means for connecting said motor to said source, means for effecting the retardation of the speedof said motor, including a switching device normally inoperative when said motor is rotating, and means, responsive to the operation of I said control means to stop said motor, for

effecting the operation of said switching device, the operation of said switching device effecting the actuation of said switching means to connect said motor to said source as for rotation in a direction opposite to the direction in which the motor is rotated, whereby the said motor is retarded.

10. In combination, a motor, a source of power for said motor, control means operable to reversibly start and stop said motor, switching means actuable in response to the operation of said control. means, for connecting said motor to said source, means for effecting the retardation of. the speed of said motor upon the operation of said control means to stop said motor, said means including a switching device which is normally n an inoperative condition while said motor is moving but which is selectively operable when the said control means is operated to stop said motor, for efl'ecting the actuation of said switchin means as for a direction of movement of said motor opposite to that in which the motor is moving, whereb said motor is retarded, and 'means, inc ud ng means operably responsive to the operation of said control means to stop said motor, for selectively operating said switching device.

11. In combination, a motor, a source of power for said motor, control means operable to reversibly start and stop said motor, switching means actuable in response to the operation of said control means, for connecting said motor to said source, means for effecting the retardation of the speed of'said motor from the time said control means operated to stop said motor until said motor is stopped, said means including a switching device, which is in an inoperative condition when said motor is moving under normal operation but which is selectively operable when said control means is operated to stop said motor, for efiectin the actuation of said switching means as or the operation of said motor in a direction opposite to that in which the motor is moving, means, including means responsive to thevoperation of said control means to stop said motor, f or selectively operating said switching device when said control means is operated to stop said motor, and for continuing to operate said switching device until said motor starts to reverse its direction of movement, the said operating means for said switching device beunder normal ing responsive to a change in direction of movement of the motor for causing saidswitching device to return to its inoperative condition, the return of said switching device to its inoperative condition efl'ecting the actuation of said switching means to disconnect said motor from said source and thereby stop said motor.

12. In combination, a motor, a source of power for said motor, control means operable to reversibly start and stop said motor, switching means actuable in response to the operation of said control means, for connecting said motor to said source, means for effecting a retardation of the speed of said motor, including a switching device which is normally in an operative condition while said motor is moving but which is selectively operable when said control means is operated to stop said motor, for eflecting the actuation of said switching means as for a direction of movement of said motor opposite to that in which the motor is moving, whereby said motor is retarded, and means for selectively operating said switching device in response to the operation of said control means to stop said motor, said last mentioned means comprising two relatively m'ovable elements normally disengaged from each other, one of said elements being movable in accordance with the movement of said motor, the other of said elements disposed to engage said movable element and be moved thereby to effect the selective operation of said switching de vice, and means operably responsive to the operation of said control means to stop said motor, for eifecting the engagement of said two elements.

13. In combination, a motor, a source of power for said motor, control means operable to reversibly start and stop said motor, switching means actuable in response to the operation of said control means, for connecting said motor to said source, means for offooting a continuous retardation in the speed of said motor from the time said control means is operated to stop said motor until said motor is stopped, said means including a switching device, which is in an inoperative condition while said motor is moving operation but which is selectively o erable when said control means is operate to stop said motor, for effecting the actuation of said switching means as for the operation of said motor in a direction opposite to that in which the motor is movin means for selectively operating said switc ing device, including two relativel movable elements normally disengaged rom each other, one of said elements being movable in accordance with the movement of said motor, the other of said elements being disposed to engage said movable element and be moved thereby to efi'ect the selective operation of said switching device, means operably responsive to the o eration of said control means to stop sai motor, for effecting the engagement of said two elements, and means controlled by the position of the other of said two elements for maintaining said last mentioned means effective as long as the said motor moves in its original direction.

In testimony whereof, I have hereunto subscribed my name this 11th day of February,

RAY P. HIGBEE. 

